If I you have to mix a gallon of liquid solution 3 parts water and 1 part alcohol, how much alcohol do you mix in?

1 quart alcohol and 3 quarts water

If the alcohol is absolute alcohol to make 1 gallon (4 quarts), then mix in 3 quarts water and 1 quart alcohol.

However, most of the time, alcohol comes in 96.5% alcohol, then we will define x=volume of alcohol in gal, then 1-x=volume of water, and solve following equation for x:

0.965x + (1-x) * 0=0.25

x=0.25*0.965=0.259 gal

will need 0.259 gal of 96.5% alcohol and 0.741 gal. of water.